Why do you use expressjs? [closed]

Express.js is a Node framework that can be compared to Laravel for PHP, it creates route abstractions, middlewares, and many other functions to facilitate the creation of both API's and SPA's.

A cool example of using it is exposing a simple get API that can be done in just a few clicks in less than 10 minutes.

Now, do not confuse Angular and Express, Angular.js is a front-end library while Express is a Back-end framework, angular is concerned with facilitating the life of the programmer when it comes to data processing and display, Express is focused on creating and obtaining data from your server. Regardless of the language that will use them.

I would say that they are complementary , but not equal, nor can they be compared.

On your second question, it is not only advisable to use Express.js with Angular.js, just like any other framework or front-end library (such as React.js or Polymer). See that Express, as a Back-End framework, can be used with any language that consumes your data.